Screen printed resistors are used extensively in many types of electronic products. For example, a circuit board in a cellular handset can have more than 200 resistors. In many instances, these are embedded within a layer of the circuit board, so as to leave room for larger parts on the exposed surfaces. Embedded resistors are presently fabricated with width and length as small as 250 microns, using laser trimming to obtain a desired value within an acceptable tolerance (e.g., 1%). It is desirable to reduce the dimensions of the resistors, consistent with overall product size reduction. Even the current dimensions, however, are challenging. Reducing width substantially below 250 microns is difficult, because typical minimum laser kerfs are about 50 microns, making it difficult to fine tune the resistor value within acceptable tolerances. Reducing length substantially below 250 microns is difficult, even when the width is greater than 250 microns, because a second laser kerf, either parallel to or perpendicular to the first cut, is typically used to fine tune the resistor value after a first kerf has been used for coarse tuning, and very short resistors will not accommodate a second cut.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.